For the past several weeks I have a specific member that will receive an "elite" undead march on wave 5,10,15 and 20. This wave is only undead ground troops and a larger number in total than a corresponding regular undead march. What criteria is used to determine who will receive elite undead waves? We have compared accounts and cannot determine any specific factor that would trigger an elite march. This has been consistent with only this player each week, leading me to believe it is not random. Please advise. Thank you!